Compression resistant zinc base alloy

ABSTRACT

ZINC BASE ALLOY CONSISTING OF, BY WEIGHT, 2-25% OF ALUMINUM, 1-10% OF COPPER, 0.01-1.5% OF MAGNESIUM, 0.02-0.15% OF BERYLLIUM, 0.01-1.5% OF TITANIUM, AND ZINC FOR THE BALANCE HAS SUPERIOR COMPRESSION RESISTANCE EXTENDING TO 110 KG./MM.2 OF COMPRESSIVE STRENGTH AND 78 KG./MM.2 OF YIELD POINT ON COMPRESSIVE DEFORMATION.

Marc 1971 TAKEHIRO ISOBE L 3,567,436

CQMPRESSION RESISTANT ZINC BASE ALLOY Filed April 26, 1968 Compression ratio.

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BY ism/om IIGA rromvgys States Patent Oce Patented Mar. 2, 1971 U.S. Cl. 75178 13 Claims ABSTRACT OF THE DISCLOSURE Zinc base alloy consisting of, by weight, 225% of aluminium, l% of copper, 0.01l.5 of magnesium, 0.020.15% of beryllium, 0.0l1.5% of titanium, and Zinc for the balance has superior compression resistance extending to 110 kg./mm. of compressive strength and 78 kg./mm. of yield point on compressive deformation.

This invention relates to an improvement in zinc base alloys, and more particularly concerns a compression resistant zinc base alloy having superior resistance properties such as 110 kg./mm. of compressive strength and 78 kg./mm. of yield point on compressive deformation.

Heretofore, a zinc base alloy has been proposed named Zamak 2 containing 3.5-4% of aluminium, 3.54% of copper, 0.030.06% of magnesium as a compression resistant zinc base alloy for good performance as forming die.

However, previous zinc base alloys including Zamak 2 have not proved entirely satisfactory because they have less than about 65 log/mm? of compressive strength and 45 kg./mm. of yield point on compressive deformation at best.

Accordingly it is an object of this invention to provide a zinc base alloy having high compressive strength and high yield point on compressive deformation.

It is another object to provide a zinc base alloy having enough high fluidity and castability to be used for a gravity casting process offering a beautiful casting surface. It is another object to provide a zinc base alloy preventing intermetallic corrosion.

Other objects and advantages of this invention will further become apparent hereinafter.

It was found that a zinc base alloy containing, by weight, 225% of aluminium, 1-10% of copper, 0.01 0.5% of magnesium, 0.02-0.15% of beryllium and 0.001-1.5% of titanium-as alloy constituents, has superior compression resistance and is suitable for casting.

Each limitation is based on the following reasons. In this invention, addition of beryllium to the alloy improves compression resistance and 0.02% or more of beryllium prevent intermetallic corrosion not accompanied by deterioration of castability, however beryllium over 0.15% makes it difficult to alloy and moreover the alloys become expensive.

Titanium also improves the compression resistance in cooperation with beryllium, however addition of titanium over 1.5% causes segregation.

Addition of aluminium in a range of 2-25% gives the most desirable compression resistance. Furthermore, from a viewpoint of compression resistance, the added amount of copper is specified in a range of 110%; contrariwise, addition of copper over 10% has a bad in fluence on the metallographic structure, for example, the grain size of the structure becomes rough and another phase sometimes occurs. 0.01% or a higher amount of magnesium acts to prevent intermetallic corrosion, however if over 0.5% thereof is added, the brittleness of the alloy is increased.

Magnesium may be replaced by beryllium in the extent satisfying the following equation without causing any bad effect.

Mg percent+Be percent;0.03%

If the amounts of each alloy constituent are not kept within the above limitations, compression resistance is markedly deteriorated or other properties are affected, for example, fluidity is decreased or brittleness is increased.

In addition to compression resistance, the zinc base alloy of this invention has the following properties:

(1) The melting point varies from 390540 C., in conformity with the aluminium and copper content percent.

(2) The fluidity is slightly deteriorated, in conformity with an increase of the aluminium or copper content percent, however the zinc base alloy has a sufliciently high fluidity to produce cast products having complicated forms and beautiful casting surfaces by diecasting or gravity casting.

(3) Usual zinc alloys containing aluminium tend to suffer an intermetallic corrosion caused by the impurities included therein, such as lead, tin, cadmium and indium; however, in the alloy of this invention, intermetallic corrosion is prevented by addition of magnesium and/or beryllium. Thus, after steam treatment for 240 hours at a temperature of :5 C., there arises a change in size of not more than 0.15%.

(4) A plating may be carried out as easily as the plating for a common Zinc base alloy.

(5) The specific gravity of this alloy is 5.8-6.9.

The zine base alloy of this invention has numerous advantages, especially, kg./mm. of superior compression resistance and 78 kg./mm. of yield point on compression deformation and suitability for die-casting and gravity casting sufiicient to gain a beautiful casting surface.

The zinc base alloy has many uses such as shaping material, piston material, pressure instrument parts, spring boxes, machine parts, bearings and type.

For the purpose of giving those skilled in the art a better understanding of the invention as well as a better appreciation of advantages of the invention, the following examples of the invention are given by way of illustration.

The invention is also illustrated by the figure of the attached graphs.

EXAMPLE Specimens being 8 mm. in diameter and 12 mm. in height, which were made by a series of ZnAl-Cu (Mg)BeTi alloys listed in Table I, were used for a motor compression testing machine, and compressive strength and yield point of compressive deformation were measured.

Those values, as well as hardness and tensile strength of each alloy, are set forth in Table II.

of this invention (Sample No. 14) and curve B represents the known alloy Zamak 2. The zinc base alloy of this invention is about 70% superior in the property to Zamak 2 which is well known as a compression resistant zinc alloy.

We claim:

1. A compression resistant zinc base alloy which consists of, by weight, 2-25% of aluminum, 110% of copper, 0.010.5% of magnesium, 0.020.15% of beryllium, 0.011.5% of titanium and the balance of zinc.

2. A compression resistant zinc base alloy according to claim 1, wherein magnesium is replaced at least partially by beryllium satisfying a formula of Mg percent+ Be percentg0.03%. 3. A compression resistant zinc base alloy according to claim 1 having a compressive strength of from 70 to 110 kg./mm. and a yield point on compressive deformation of from 50 to 78 kg./mm.

4. A compression resistant zinc base alloy according to claim 1 consisting essentially of 2.0% A1, 3.0% Cu, 0.04% Mg, 0.04% Be, 0.1% 'Ti and the remainder zinc.

5. A compression resistant zinc base alloy according to claim 1 consistingessentially of 4.0% A1, 3.0% Cu, 0.04% Mg, 0.04% Be, 0.1% Ti and the remainder zinc.

6. A compression resistant zinc base alloy according to claim 1 consisting essentially of 6.0% A1, 3.0% Cu, 0.04% Mg, 0.04% Be, 0.1% Ti and the remainder zinc.

7. A compression resistant Zinc base alloy according to claim 1 consisting essentially of 10% A1, 3.0% Cu, 0.04% Mg, 0.04% Be, 0.1% Ti and the remainder zinc.

8. A compression resistant Zinc base alloy according to claim 1 cdnsisting essentially of 2.0% A1, 7.0% Cu,

TABLE I Alloy constituents, percent Sample No. Al 011 Mg Be Ti Zn Known art for OOHIIJEI'ISOBZ 4. 0 1.0 0. 04 0. 04 0. 1 DO. 2.0 3.0 0 04 0. 04 0.1 Do. 5 4. G 3.0 0. 04 0. 04 0. 1 D0. 4.0 3.0 0.04 0.1 Do. 0. 0 3. 0 0. 04 04 0. 1 D0. 10. 0 3. 0 0. 04 0. 04 0. 1 D0. 2.0 7.0 0.1 0.1 0.3 Do. 4. 0 7. 0 0. 1 0. 1 0. 2- D0. 6. 0 7. 0 0.1 0. 1 0. 3 DO. 6.0 7.0 0.1 0.3 Do. 10.0 7. 0 0.1 0. 1 0. 3 DO. 10.0 10. 0 0. 1 0. 15 1. 5 D0. 15. 0 3. 5 0. 9 0. 04 0. 9 D0. 20. 0 3. 1. 2 0. 04 1. 2 Do. 25. 0 3. 5 1. 5 0. 04 1. 5 D0. 25. 0 10.0 1. 5 O. 15 1. 5 D0.

TABLE II Yield point on Tensile Compressive compressive Hardness strength strength deformation Sample No. (H (kgJmmfl) (kg/mm?) (kg/mm?) For comparison:

Result: compared with Zamak 3 alloy (Japan Industrial Standard-Type 2, Sample No. 1) or Zamak 5 alloy (Japan Industrial Standard-Type 1, Sample No. 3) the zinc base alloy of this invention, samples of Nos. 6-25 show high hardness, increased tensile strength and those properties are affected by contents of beryllium and titanium. A compressive strength and a yield point on compressive deformation, also show high values. The alloys in samples of Nos. 4 and 5 in which beryllium or titanium was individ'ually added hardly show its effect. Further, referring to FIG. 1 relation of deformation resistance and compression ratio is shown. Curve A represents an alloy 0.1% Mg, .l% Be, 0.3% Ti and the remainder zinc. 9. A compression resistant zinc base alloy according to claim 1 consisting essentially of 4.0% A1, 7.0% Cu, 0.1% Mg, 01% Be, 0.3% Ti and the remainder zinc. 10. A compression resistant zinc base alloy according to claim 1 consisting essentially of 6.0% A1, 7.0% Cu, 0.1% Mg, 0.1% Be, 0.3% Ti and the remainder zine. 11. A compression resistant zinc base alloy according to claim 1 consisting essentially of 10% A1, 7.0% Cu, 0.1% Mg, 0.1% Be, 0.3% Ti and the remainder zinc. 12. A compression resistant zinc base alloy according to claim 1, in which the proportions of aluminum and copper are, respectively, 2 to 10% and 3 to 7%.

13. A compression resistant zinc base alloy according to claim 12, having a compressive strength of 95 to 110 kg./mm.-".

References Cited UNITED STATES PATENTS 2,013,870 9/1935 Starmann 75l78 3,037,859 6/1962 Larrieu 75--178 FOREIGN PATENTS 638,733 6/1950 Great Britain -1 '75--178 790,309 2/1958 Great Britain 75-178 HYLAND BIZOT, Primary Examiner E. L. WEISE, Assistant Examiner 

